Phonograph pick-up



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Feb. 28, 1.939. A' BARB|ER| 2,148,796

PHONOGR'APH P10K-UP Filed May 18, 1937 1.9 as' 22 20 24 Andres gj/'vefvf SHO: cnf

' with -the variations in the sound recordings.

Patented Feb. 28, 1939 14ans PATENT OFFICE PHON OGRAPH PICK-UP Andrs Barbieri, New York, N. Y., assignor to Amperite Company, New York, N. Y., a partnership composed of Samuel Ruttenherg and William Ruttenberg Application May 18, 1937, Serial No. 143,350

17 Claims.

This invention relates to a novel pickup for recorded sound. I

Pickups for recorded sounds in general use at the present time are either of the magnetic or dynamic type. In both of these pickups current is inducedV in a coil which varies in accordance the magnetic type of pickup, the current is induced in the coil by varying the strength of the magnetic field to which the coil is exposed. In the dynamic type of pickup the coil is moved f through a magnetic eld of uniform strength and the current induced in the coil is varied by the movement thereof. Both of these types of pickup, however, are'insuliciently responsive to low frequencies. The pickup, according to this inkvention, combines, in general, the operating characteristics of both the magnetic and dynamic types in that the coil of the device is moved and at the same time the strength of the eld through which it moves is varied. The performance of the pickup according to this invention, however, is characterized by a marked dissimilarity from the performance of the magnetic or dynamic type of pickup, having a greatly increased response at low frequencies.

It is one ofthe objects of this invention to provide a pickup which is especially responsive to recorded sounds of low frequency.

Another object ofthis invention is the provision of a pickup armature especially shaped for greatly increased response at low frequency.

A further object of this invention is the provision of a specially shaped pickup armature and poles for greatly increasing the uniformity of the response at low frequencies. i

A fourth object of this invention consists in a novel mounting for the moving armature of a phonograph pickup. f

A fifth object of this invention consists'of a combined bearing and damping member for a pickup armature.

, bearing members serve to support the armature l for rotation in the space between the poles I and 2 and at the same time dampen its vibration. 'The bearing and damping members Ill and I I are Figure 2 is a secton taken on line 2-2 of Figure 1.

Figure 3 is a bottom plan view of the device with the cover plate removed.

-Figure 4 is a diagrammatic sectional View of a 5 modification.

Figure 5 is a diagram of a series of curves illustrating certain features of the invention.

Figure 6 is a diagrammatic showing of a magnetic type of pickup.y

Figure 7 is a diagrammatic showing of a dynamic type of pickup.

Figure 8 is a diagrammatic showing of a pickup according to this invention.

Referring particularly to Figure 1 of the drawing, I and 2 are spaced magnetic poles. In the space between magnetic poles I and 2 is an armature 3 having a series of longitudinal windings 4 thereon. These windings 4 terminate at each end in a pair of contact members 5 and 6 which 20 are connected in the usual manner to a conventional output. The armature 3 has a central opening 'I formed therein adapted to receive the usual phonograph needle 8. A set screw 9 suitably threaded into the end of the armature servessecurely to retain the needle 8 in the opening 1.

The armature 3 is mounted for restricted rotation about its longitudinal axis by a pair of bearing and supporting members IIJ and II. These made of rubber or other suitable resilient material. An additional damping member I2 is mounted in a transverse central opening in the armature 3. The member I2 is made of a suitable non-magnetic and resilient material.

A permanent magnet I3 is positioned between poles I and 2. The poles I and 2 being made of steel or other suitable para-magnetic material therefore serve to concentrate the lines of force running from one pole to the other of the permanent magnet I3 and are thus in themselves north and south poles of the magnet I3. The 'pole pieces I and 2 are not permanently magnetized but are merely of para-magnetic material such as steel or iron. The armature 3 and coil 4 are protected by cover plates I E-and I1 held in place by suitable screws I8.

The adjacent faces of the pole pieces I and 2 are preferably, though not necessarily, arcuate in shape as indicated at III and I5, respectively.

In the modification as diagrammatically illustrated in Figure 4 the pole pieces Ia and 2a are 55 shown having at faces Ida and i5a. In this modification the armature is indicated diagrammatically at 3a, the windings at #la and the needle at 8a.

Essentially, the pickup according to this invention, combines some of the characteristics of the magnetic and dynamic types of pickup. The usual form of magnetic pickup is illustrated diagrammatically in Figure 6. It consists of a moving armature I9 of steel or other para-magnetic material pivoted at 253 and vibrating between a pair of poles 2l and 22, respectively. Surrounding the armature i9 is a stationary coil 23. The movement of the armature i9 changes the flux passing through the armatureand hence through the stationary ccil 23. As may be noted in Figure 6 some of the magnetic lines oipforce are shown passing through 'thelarmatu're IB due to the position thereof. The movement of armature is, of course, caused by the corresponding lmovement of needle 24.

"stationary and only serv-es to concentrate the strength ofthe magnetic field where it is cut by the moving coil 2l.

Figure 8 is a diagram-maticrepresentation of a -pickup'accordingto =thepresent invention. Both the coil 4 and the armature '3 move`-in'the magnetic field produced by'poles l and2 inaccordance with the movement of`needle`8. As shown lin B 'igure Y8 theflines f 'force between'p'oles l r`and? are twisted 'by the position of armatureS. This change 'in the lines of force'is vsomewhat V'ajr'ialogous to the change produced-vby'armature i9 fas shown'inFigure 6. vAt the s-ame time current is also induced in coil 4 by the movement of the coil relative to 'the lines efforce in "'a manner The total current induced in the coil `4,' i therefore, is inuerfced by'the two changing factors landthe pickup, therefore, 'partakes ofthe 'char- `acteristics of both `the dynamic Aand magnetic -types of pickup.

The 'greatly increased response at `low frequencies of the pickupaccordingtdthe present invention is clearly illustrated in the curves designated A and B lofl'igu're 5. `These curves show 'vtheresp'onselof various types of vpickups atvarious frequencies. The response in -decibels -is plotted alongthevertical axis and' the frequency -along the horizontal.

The 'curve denoted A `is theres'ponse curve ofthe modification having'atpoles f'as-illustrated in Figure 14. The curve'B'is theresponse curve of'thefform vof the invention v illustrate'd'in Figures 1, 2 and 3; thecurve C, is adynamictype of pickup as illustrated in Figure "7; Vand thecurve D, that'f aimagnetictype of Ipickup as illustrated in-"Figure, In all of these testsa standard "frequency record was used'for the input, andthe output was measured Yby meansv of `a vacuum tube `voltmeter.

VIt will be readily understood that thedevice as fdescribedin the drawing and specification may be variedwithout departing from the spirit of the invention. For example, the shapeof the armature maybe any rectangular form or may be oval in form instead of square as shown. I'he magnetic poles may be permanent magnets or any conventional form of electromagnet. .The shape of the magnetic poles-may also bev-aried. ,Various other modications'may also be made without departing from the spirit of the invention. I do not wish the scope of my patent to be limited except as dened by the claims annexed hereto.

What I claim as new and desire to secure by Letters Patent is:

1. In a pickup for recorded sounds, means movable in accordance with 'the recorded variations of the sounds, means for producing a magnetic yield, an elongated core member movable with the rst mentioned means and adapted to change 'the p'athof the magnetic flux of said magnetic eld, a conductor .positioned so that the longitudi- "nal axis'the'reof is colateral with the longitudinal axis of 4said -core member and arranged to move withsaid core member in a direction to induce a response therein influenced both by its -owndmov'e'rnent in said magnetic eld and the change inthe path of the flux of said magnetic eld, and an output for said conductor.

25111 -a Ypickup for recorded sounds, means movable in accordance with therecorded varia- 'tions of the soundsfamagnet, a coil positioned Vlin' the' field off said magnet so thatthe plane-there- -ofis substantially-parallel to the lines of force of said field, means for -moving-said coil in-accordance with the-movement-offsaid first mentioned Vmeans in a direction to cutthe magnetic lines of force in said held, means for simultaneously Ycha'ngin'g'the path-of the flux of said magnetic eld, andan outputffor said coil.

i3. vIn -a pickup for recorded soundsymeansvfor Eproducing-a vmagnetic field, lmeans movable in accordance vwith'the recorded Avariation of the -soun'ds,"an `armatureeinfsaid magneticfield movv"able with the last `mentioned Lmeansand constructed and arranged -to changefthe `path of -theflux-in said'field, a coil positioned on said armature so 'that the plane thereof is substan- -tallyfpaillel t0 the lines of force 0f said field v`andTmovalole"therewithfin a direction to cut the VA'in'agnetic-lines of force in: said field and an output for saidcoil. I

"4. Inma'pickupforrecorded sounds,-a magnet,

-apairof spaced pole'membersarranged and constructed to concentrate the magnetic leld of said magnet in the spaceb'etwen saidlpole members,' ana'rmature movably Amounted' inthe space between said polemembers constructedfand arranged -to change the pathof the uX in vsaid ieldza coil carried by said rarrria'tureand movabletherewith inadirection to cutthe magnetic '-li'nes offorcein said eld and an output for said coil.

'5. In1-a`pickup forrecorded sounds, apair of spaced pole members, a magnet positioned beltween lsaid spaced 'pole `me'mbers,lan armature movabl'y mounted between said'poles,'a-coil carried by the armature, and acOmbnedbearing land'damping member for vsupporting said-armature.

6. In a pickup for recorded-sounds, av pairiof spaced pole members, amagn'et positioned between said pole membersand an armature of `-square cross-section mounted for rotational movement so as to change the path of the mag- 8. In a pickup for recorded sounds, a pair of spaced pole members, said pole members having adjacent faces of arcuate shape, a magnet positioned between said pole members, an armature movably mounted between said pole members, a coil wound about said armature parallel to the longitudinal axis thereof, means for moving said armature and coil and an output for said coil.

9. In a pickup for recorded sounds, a pair of spaced pole members, said pole members having adjacent faces of arcuate shape, a magnet positioned between said pole members, an armature of square cross-section mounted between said pole members for rotational movement, a combined ture parallel to the longitudinal axis thereof and an output for said coil.

10. In a pickup for recorded sounds, a pair of spaced pole members, said pole members having adjacent faces of arcuate shape, a magnet positioned between said pole members, an armature of square cross-section mounted between said pole members for rotational movement, a coil wound about said armature p-arallel to the longitudinal aXis thereof and movable therewith and an output for said coil.

11. In a pickup for recorded sounds, a pair of spaced pole members, said pole members having adjacent faces of arcuate shape, a magnet positioned between said pole members, an armature movably mounted between said pole members, a combined bearing and damping member for supporting said armature, a coil wound about said armature parallel to the longitudinal axis thereof and movable therewith and on output for said coil.

12. In a pickup for recorded sounds a member movable in accordance with the recorded variations of the sounds, a pair of spaced pole members, a magnet positioned between said pole members, an armature movably mounted in the space between said pole members and constructed and arranged to vary the path of the flux in said field, a coil wound about said arm-ature parallel to the longitudinal axis thereof movable therewith, means on said armature for supporting the rst mentioned member so that the armature moves with said member, and an output for said coil.

13. In a pickup for recorded sounds, a pair of spaced pole members, an armature mounted in the space between said pole members, a coil carried by said armature and a combined bearing and damping member for supporting said armature comprising a sleeve of resilient material.

14. In a pickup for recorded sounds, a member movable in accordance with the recorded variations of the sounds, a pair of spaced pole members, an armature mounted in the space between said pole members, a coil carried by said armature, a combined bearing and damping member for supporting said armature comprising a sleeve of resilient material and means on said armature for supporting said first mentioned movable member.

l5. In a pickup for recorded sounds, means for producing a magnetic field, means movable in accordance with the recorded variations of the sounds, an armature in said magnetic eld movable with the last mentioned means and a coil positioned on said armature so that the plane thereof is substantially parallel to the lines of force of said eld, said armature being constructed and arranged to vary the path of the lines of force of said magnetic field, and said coil being constructed and arranged to cut the varying lines of force when moved in the magnetic eld, and an output for said coil.

16. In a pickup for recorded sounds, means movable in accordance with the recorded variations of thesounds, means for producing a magnetic eld, spaced means to concentrate said field in the space therebetween, means positioned in said space movable with the rst mentioned means and adapted to change the path of said flux in said space, and a conductor movable with said rst mentioned means in said space in a direction to produce a response influenced both by its own movement in said magnetic field and the change in the path of the iiux of said magnetic iield, and an output for said conductor.

17. In a pickup for recorded sounds, means 

